Flame and Heat Resistant Oilfield Tools

ABSTRACT

Oil and gas well tools, tool components, and explosive components having a heat resistant and/or flame retardant coating are provided. Furthermore containers and packing material having a heat resistant and/or flame retardant coating for use in transporting heat and/or flame-sensitive tools, tool components, explosives, and explosive components are provided.

BACKGROUND OF INVENTION

The present invention relates generally to fire resistant well tools andcomponents, and more particularly to a perforating gun assemblyprotected by a heat resistant and/or flame retardant coating.

Well operations typically involve the use of tools and tool componentsthat are heat or flame-sensitive or even explosive when exposed to hightemperature stresses or fire. For example, one operation that isperformed in completing a well using an explosive tool is the creationof perforations in a formation. This is typically done by lowering aperforating gun string containing explosive shaped charges to a desireddepth in a wellbore and activating the gun string to fire the shapedcharges. The shaped charges when fired create perforating jets that formholes in surrounding casing as well as extend perforations into thesurrounding formation.

The handling of perforating tools (e.g., charge carriers, loading tubes,detonators) or explosive components (e.g., shaped charges, propellants,actuators) during transportation, assembly, and operation necessarilyinvolves the risk of exposure to heat or flame. Such exposure may damagethe tools resulting in faulty operation, or worse ignite the explosivecomponents causing bodily injury and/or severe damage to property.

A need thus exists for a method and apparatus to protect heat and/orflame-sensitive well tools, and explosive tool components and elements.

SUMMARY OF INVENTION

In general, according to an embodiment, the present invention providesheat resistant and/or flame retardant oil and gas well tools andexplosive tool components.

For example, embodiments of the present invention include well tools andexplosive tool components protected by a heat resistant and/or flameretardant coating.

In general, according to another embodiment, the present inventionprovides heat resistant and/or flame retardant containers and packingmaterial for shipping, transporting, packaging, and/or storing oil andgas well tools, explosive tool components, and explosives.

For example, embodiments of the present invention include containers andpacking material protected by a heat resistant and/or flame retardantcoating for storing, shipping, and packaging well tools, explosive toolcomponents, and explosive.

Other or alternative features will be apparent from the followingdescription, from the drawings, and from the claims.

BRIEF DESCRIPTION OF DRAWINGS

The manner in which these objectives and other desirable characteristicscan be obtained is explained in the following description and attacheddrawings in which:

FIG. 1 is a profile view of a typical perforating gun being run down acased wellbore.

FIG. 2A is a cross-sectional view of a non-capsule shaped charge and anembodiment of the protective coating of the present invention.

FIG. 2B is a profile view of a set of capsule charges and an embodimentof the protective coating of the present invention.

FIG. 3A is a profile view of a perforating gun illustrating theassembled shaped charge, loading tube, and hollow carrier and anembodiment of the protective coating of the present invention.

FIG. 3B is a cross-sectional view of the perforating gun depicted inFIG. 2A illustrating the shaped charge, loading tube, and hollow carrierand an embodiment of the protective coating of the present invention.

FIG. 4 is a sectional view of an exploding foil initiator and anembodiment of the protective coating of the present invention.

FIG. 5 is a profile view of a detonator assembly illustrating theassembled detonator, initiator, processor, and power supply with anembodiment of the protective coating of the present invention.

FIG. 6 is an isometric view of a container and packing material forholding one or more shaped charges, and an embodiment of the protectivecoating of the present invention.

It is to be noted, however, that the appended drawings illustrate onlytypical embodiments of this invention and are therefore not to beconsidered limiting of its scope, for the invention may admit to otherequally effective embodiments.

DETAILED DESCRIPTION

In the following description, numerous details are set forth to providean understanding of the present invention. However, it will beunderstood by those skilled in the art that the present invention may bepracticed without these details and that numerous variations ormodifications from the described embodiments may be possible.

In the specification and appended claims: the terms “connect”,“connection”, “connected”, “in connection with”, and “connecting”areused to mean “in direct connection with”or “in connection with viaanother element” the term “set”is used to mean “one element”or “morethan one element” and the term “downhole tool”is used to mean “anexplosive well tool”, “an explosive well tool component” and/or “anexplosive for use in well operations”. As used herein, the terms “up”and“down”, “upper”and “lower”, “upwardly”and downwardly“, “upstream”and“downstream” “above”and “below” and other like terms indicating relativepositions above or below a given point or element are used in thisdescription to more clearly described some embodiments of the invention.However, when applied to equipment and methods for use in wells that aredeviated or horizontal, such terms may refer to a left to right, rightto left, or other relationship as appropriate.

Generally, a protection system is provided for shielding explosive toolsand/or explosive tool components from exposure to high temperaturestresses or fire. More particularly, embodiments of the presentinvention include oil and gas well tools having explosivecomponents—such as perforating tools—having a heat resistant and/orflame retardant coating to prevent detonation during a fire or exposureto heat and flame.

In embodiments of the present invention, any heat resistant and/or flameretardant coating (also referred to herein as “thermal coating”) may beused to protect a well tool or tool component. For example, FX-100®coating by Flame Seal Products, Inc. is a Class A, super-intumescentcoating which may be applied to a variety of materials including, butnot limited to, metal, plastic, wood, paper, and other porous ornon-porous materials. FX-100® coating forms a thick, insulating barrierwhen exposed to fire. Another example is Albi Clad 800™coating by AlbiManufacturing. Albi Clad 800™ coating is a solvent-based, intumescentmastic fire protective coating capable of resisting weathering andsevere environmental stresses and is applicable to many materialsincluding, but not limited to, steel, concrete, and other constructionmaterials. Albi Clad 800™expands from a thin coating into a foam-likesubstance when exposed to fire. Yet another example is Corr-Paint™CP40XX coating by Aremco Products, Inc. Corr-Paint™CP40XX coating is aseries of silicone-based, heat resistant coatings formed using awater-dispersable silicone resin. Corr-Paint™ CP40XX coatings adhere tovarious materials including, but not limited to, metals, ceramics,refractories, and quartz, and are resistant to outdoor weathering, UVlight, salt spray, chemical corrosion, thermal cycling. Whileembodiments of heat resistant and/or flame retardant well tools and toolcomponents in accordance with the present invention may be manufacturedand used with any one or a combination of these particular coatings, itis intended that other embodiments may use any one or combination of anyother heat resistant and/or flame retardant coatings.

In producing heat resistant and/or flame retardant well tools, a thermalcoating may be applied to the surface of the well tools or toolcomponents by brush, roller, spray or other application method.

An embodiment of the present invention includes heat resistant and/orflame retardant perforating tools. FIG. 1 illustrates a conventionalperforating system including a plurality of shaped charges 10, which maybe conveyed downhole via a hollow carrier gun 30. Within the hollowcarrier 30, a loading tube 40 is positioned. The loading tube 40includes a plurality of openings proximal, for receiving and mountingthe shaped charges 10. Generally, a series of hollow carrier guns may beassembled to form a perforating gun string 50 having a desired length.An example length of each gun may be about 20 feet. To make aperforating gun string 50 of a few hundred feet or longer, several gunsmay be connected together in series by adapters 52. Each of the adapters52 contains a ballistic transfer component, which may be in the form ofdonor and receptor booster explosives. Ballistic transfer takes placefrom one gun to another as the detonation wave jumps from the donor tothe receptor booster. At the end of the receptor booster is a detonatingcord that carries the wave and sets off the shaped charges in the nextgun. Examples of explosives that may be used in the various explosivecomponents (e.g., shaped charges 10, detonating cord 14, and boosters)include RDX, HMX, HNS, TATB, and others. Moreover, a propellant materialin the form of a sleeve, strip, patch, or other configuration may bepositioned in the path of the shaped charges 10 to enhance theperforations and to stimulate the surrounding formation.

Once assembled, the gun string 50 is positioned in a wellbore 60 that islined with casing 62. A tubing or pipe 64 extends inside the casing 62to provide a conduit for well fluids to wellhead equipment (not shown).A portion of the wellbore 60 is isolated by packers 66 set between theexterior of the tubing 64 and the interior of the casing 62. Theperforating gun string 50 may be lowered through the tubing or pipe 64on a carrier line 70 (e.g., wireline, slickline, or coiled tubing). Oncepositioned at a desired wellbore interval where the gun string 50 isfired to create perforations in the surrounding casing and formation. Inthe event that a propellant material is used, the firing of theperforating gun 50 ignites the propellant material thereby generating apressurized gas from the burning of the propellant material. The gaspenetrates the formation via the perforations and cleans the perforationtunnels by pushing out debris. The pressurized propellant gas may alsostimulate the surrounding formation to facilitate production byfracturing the formation.

FIG. 2A illustrates an embodiment of the present invention, whichincludes a coated non-capsule shaped charge 10. The shaped charge 10 hasan outer case 12 that acts as a containment vessel designed to hold thedetonation force of the detonating explosion long enough for aperforating jet to form. Common materials for the outer case 12 includesteel or some other metal. A main explosive charge 16 is containedinside the outer case 12 and is sandwiched between the inner wall of theouter case 12 and the outer surface of a liner 20. A primer column 14 isa sensitive area that provides the detonating link between the mainexplosive charge 16 and a detonating cord 15, which is attached to therear of the shaped charge 10. The entire shaped charge is coated with athermal coating 11 to protect the charge from exposure to hightemperature and/or fire.

Alternatively, an embodiment of the present invention may also include acapsule charge having a thermal coating for protection from heat and/orflame. For example, as shown in FIG. 2B, a linear strip 80 may includeone or more capsule charges 82, each having a thermal coating 83. Thecapsule charges 82 may be mounted together via a retaining bracket 84with a detonating cord 86 attached to the back of each capsule charge.

FIGS. 3A and 3B illustrate another embodiment of the present invention,which includes a coated perforating gun assembly. The perforating gunassembly includes a plurality of shaped charges 10, which may beconveyed downhole via a hollow carrier gun 30. The shaped charges 10 maybe non-capsule charges since the shaped charges are protected from theenvironment by the hollow carrier 30, which is typically sealed. Thehollow carrier 30 may also include a plurality of recesses 32 formed inthe outer wall. The recesses 32 are typically localized areas where thewall thickness of the carrier 30 is reduced to facilitate penetration bythe shaped charges 10. Within the hollow carrier 30, a loading tube 40is positioned. The loading tube 40 includes a plurality of openings 42proximal, for receiving and mounting the shaped charges 10. The openings42 of the loading tube 40 are typically aligned with the recesses 32 ofthe hollow carrier 30. The perforating gun assembly further includesthermal coatings 11, 34, and 44 covering one or more of the shapedcharges 10, the carrier 30, and the loading tube 40 respectively. Inanother embodiment, end connectors 45 and adaptors 52 (FIG. 1) forconnecting multiple perforating gun assemblies to form a perforatingstring 50 are also coated with a thermal coating. Moreover, while theperforating gun assembly of FIG. 3 includes a carrier 30, a loading tube40, and one or more shaped charges 10, all of which have a thermalcoating, it is intended that other embodiments of the present inventioninclude any combination of protected components including, but notlimited to, coated shaped charges 10 only, a coated carrier 30 only, acoated loading tube 40 only, or other combinations of coated perforatingtool components.

In embodiments of the present invention, the loading tube 40 may befabricated from conventional metal materials (e.g., tubular steel, pipe,sheet metal, or equivalent materials) or non-metal materials (e.g.,stamped and/or molded paper pulp, plastic, high-density polystyrene, orother equivalent materials). In these embodiments, the coating 44 isapplied onto the metal or non-metal material.

In other embodiments, the heat resistant and/or flame retardantperforating assembly may include propellant material positioned outsidethe gun 50 or casing 62 (FIG. 1) for cleaning debris from theperforating tunnels and stimulating the formation. In accordance withthe present invention, the propellant material may be coated with athermal coating to prevent an accidental ignition. In operation, whenthe perforating gun 50 is fired, the shock and heat generated from thedetonated shaped charges 10 penetrate the coating around the propellantmaterial and ignites the propellant material.

While some embodiments of the present invention have been described withrespect to a heat resistant and/or flame retardant perforating gun, itis intended that other embodiments include other explosive well toolshaving a thermal coating including, but not limited to, an explosivetubing cutter. An example of an explosive tubing cutter is described inU.S. patent application Ser. No. 10/017,116, published as US 2003/011120A1, which is incorporated herein by reference. As with embodiments ofthe perforating gun described above, embodiments of the explosive tubingcutter may include a carrier or housing coated with a thermal coating,at least one shaped charge coated with a thermal coating, or both.

Another embodiment of the present invention includes heat resistantand/or flame retardant explosive components. For example, detonators,detonating cords, firing heads, initiators, charges, switches, processorunits, power supplies, and other explosive components may be coated witha thermal coating to protect from damage or inadvertent ignition duringmanufacturing, shipping, packaging, assembly, and/or operation.

FIG. 4 illustrates an embodiment of the present invention, whichincludes a heat resistant and/or flame retardant exploding foilinitiator (EFI) 100. The EFI 100 is coated with a thermal coating 110.

FIG. 5 illustrates another embodiment of the present invention, whichincludes a heat resistant and/or flame retardant detonator assembly 200for detonating an explosive. In this particular embodiment, thedetonator assembly 200 includes safety components to avoid accidentalfiring during rig-up or rig-down, and/or to disarm an attachedperforating gun (or other ballistic assembly) if downhole conditions areunsafe for firing. Particularly, the detonator assembly 200 includes anEFI 100 in connection with a capacitor discharge unit (CDU) 210 firesetfor firing the detonator 200; an initiator board 220 in connection withthe CDU 210 for supplying the energy pulse to the CDU 210; a processor230 in connection with the initiator board 220 for receiving andverifying the firing command; and a battery 240 in connection with theprocessor 230 for supplying power to initiate the detonator 200. Theentire detonator assembly 200 is coated with a thermal coating 250. Inother embodiments, the entire assembly is not coated, but rather onlyparticular components or a combination of components are coated with thethermal coating 250.

While the embodiment shown in FIG. 5 includes a detonator having asafety system, it is intended that other embodiments of the presentinvention include a thermal coating applied to any conventionaldetonator or device containing a primary explosive material that is usedto initiate an explosive sequence. For example, an embodiment of thepresent invention may include a heat resistant and/or flame retardantelectrical detonator (or blasting cap) having a fuse material that burnswhen high voltage is applied to initiate the primary high explosive. Asanother example, an embodiment of the present invention may include mayinclude a heat resistant and/or flame retardant percussion detonatorcontaining abrasive grit and a primary high explosive in a sealedcontainer that is activated by a firing pin. In this example, the impactforce of the firing pin is sufficient to initiate the ballistic sequencethat is then transmitted to the detonating cord. These and otherdownhole detonators may be protected from exposure to heat and flame(e.g., from an accidental fire) by application of a thermal coating.

Another embodiment of the present invention includes heat resistantand/or flame retardant explosive actuators for actuating downhole toolsand/or systems by igniting an explosive. For example, U.S. Pat. No.6,651,747, which is incorporated herein by reference, includes ananchoring device for use in a perforating operation to prevent movementof a perforating gun downhole. To actuate and set the anchor device, anelectrical signal detonates a detonator release mechanism, which causesengagement mechanisms to engage the inner wall of the casing or tubing.In accordance with the present invention, the anchoring device and/orthe detonator release mechanism may be coated with a heat resistantand/or flame resistant coating to prevent accidental detonation whenexposed to heat or flame. Also, for example, U.S. Pat. No. 6,102,120,which is incorporated herein by reference, includes a downhole zonalisolation tool having an epoxy sleeve for sealing against a casing. Anembodiment of the isolation tool includes a local heat source (e.g.,thermite or some other exothermic pyrotechnic energy source) containedin a housing, which when actuated cures the epoxy sleeve. In accordancewith the present invention, the zonal isolation tool and/or the localheat source may be coated with a thermal coating to prevent accidentalignition when exposed to heat or flame.

Yet another embodiment of the present invention includes heat resistantand/or flame retardant packaging, and shipping materials for safelytransporting and storing heat and/or flame-sensitive well tools,explosives, and/or explosive components.

FIG. 6 illustrates an embodiment of the present invention, whichincludes a container 300 (e.g., a box, crate, bag, or other container)having a thermal coating 310 for holding and protecting one or moreshaped charges 10 during shipping or storage. In operation, a container300 is provided to hold the shaped charges 10—or other downhole tools.The container 300 is coated with a thermal coating 310, and the shapedcharges 10 are placed inside the container for shipping and/or storing.

Still with respect to FIG. 6, another embodiment of the presentinvention includes packing material 400 (e.g., styrofoam, plastic,paper, paperboard or other packing material) having a thermal coating410 for holding and protecting one or more shaped charges 10 in acontainer 300 during shipping or storage. In another embodiment, boththe packing material 400 and the container 300 are coated with a thermalcoating 310, 410 respectively. In operation, a container 300 and packingmaterials 400 are provided to hold and secure the shaped charges 10—orother downhole tools. The packing materials 400 are coated with athermal coating 410, and the shaped charges 10 are secured within thecontainer 300 by the packing material 400 for shipping and/or storing.

While this embodiment includes a container 300 and packing materials 400for holding one or more shaped charges 10, it is intended that otherembodiments of the present invention include containers and/or packingmaterials coated with a thermal coating for carrying any heat and/orflame-sensitive well tools, explosives, and/or explosive componentsincluding, but not limited to, perforating guns, carriers, loadingtubes, gun adapters, tubing cutters, detonators, detonating cords,firing heads, initiators, charges, propellants, explosive actuators,switches, processor units, power supplies, RDX, HMX, HNS, and/or TATBexplosives, and so forth.

Although only a few exemplary embodiments of this invention have beendescribed in detail above, those skilled in the art will readilyappreciate that many modifications are possible in the exemplaryembodiments without materially departing from the novel teachings andadvantages of this invention. Accordingly, all such modifications areintended to be included within the scope of this invention.

1. Apparatus for use in well operations, comprising: a downhole toolhaving a thermal coating.
 2. The apparatus of claim 1, wherein thedownhole tool is a perforating gun.
 3. The apparatus of claim 2, whereinthe perforating gun comprises: a hollow carrier, wherein the thermalcoating surrounds the hollow carrier.
 4. The apparatus of claim 2,wherein the perforating gun comprises: a loading tube, wherein thethermal coating surrounds the loading tube.
 5. The apparatus of claim 4,wherein the loading tube is fabricated from metal.
 6. The apparatus ofclaim 4, wherein the loading tube is fabricated from pulp paper.
 7. Theapparatus of claim 4, wherein the loading tube is fabricated fromplastic.
 8. The apparatus of claim 4, wherein the loading tube isfabricated from polystyrene.
 9. The apparatus of claim 2, wherein theperforating gun comprises: a shaped charge, wherein the thermal coatingsurrounds the shaped charge.
 10. The apparatus of claim 9, wherein theshaped charge is a capsule charge.
 11. The apparatus of claim 9, whereinthe shaped charge is a non-capsule charge.
 12. The apparatus of claim 2,wherein the perforating gun comprises: a propellant, wherein the thermalcoating surrounds the propellant.
 13. The apparatus of claim 1, whereinthe downhole tool is a tubing cutter.
 14. The apparatus of claim 13,wherein the tubing cutter comprises: a housing, wherein the thermalretardant coating surrounds the housing.
 15. The apparatus of claim 13,wherein the tubing cutter comprises: a shaped charge, wherein thethermal coating surrounds the shaped charge.
 16. The apparatus of claim1, wherein the downhole tool is a detonator.
 17. The apparatus of claim16, wherein the detonator comprises: an exploding foil initiator,wherein the thermal coating surrounds exploding foil initiator.
 18. Theapparatus of claim 16, wherein the detonator comprises: an explodingfoil initiator; a capacitor discharge unit in connection with theinitiator; an initiator board in connection with the capacitor dischargeunit; a processor in connection with the initiator board; and a batteryin connection with the initiator board, wherein the thermal coatingsurrounds the exploding foil initiator, the capacitor discharge unit,the initiator board, the processor, and the battery.
 19. The apparatusof claim 1, wherein the downhole tool is a detonating cord.
 20. Theapparatus of claim 1, wherein the downhole tool is an explosiveactuator.
 21. The apparatus of claim 1, wherein the thermal coating is athermal intumescent coating.
 22. A perforating gun for use in awellbore, comprising: a shaped charge containing an explosive; a loadingtube for holding the shaped charge; and a hollow carrier for carryingthe loading tube into the wellbore, wherein the shaped charge issurrounded by a thermal coating.
 23. The perforating gun of claim 22,wherein the loading tube is surrounded by a thermal coating.
 24. Theperforating gun of claim 23, wherein the hollow carrier is surrounded bya thermal coating.
 25. A method of protecting a downhole tool for use ina well, comprising: applying a thermal coating to the downhole tool. 26.Apparatus for use in holding a downhole tool, comprising: a containerhaving an outer surface and defining an inner volume to receive thedownhole tool; and a thermal coating applied to the outer surface of thecontainer.
 27. Apparatus of claim 26, further comprising: packingmaterial adapted to secure the downhole tool within the inner volume ofthe container, the packing material having a thermal coating. 28.Apparatus for use in securing a downhole tool, comprising: packingmaterial adapted to surround the downhole tool in a container, thepacking material having a thermal coating.
 29. A method of protecting adownhole tool, comprising: providing a container to hold the downholetool; applying a thermal coating to the container; and placing thedownhole tool within the container.
 30. The method of claim 29, furthercomprising: providing a packing material to secure the downhole tool inthe container; applying a thermal coating to the packing material; andpositioning the packing material around the downhole tool within thecontainer.
 31. A method of protecting a downhole tool, comprising:providing a packing material to secure the downhole tool in a container;applying a thermal coating to the packing material; and positioning thepacking material around the downhole tool within the container.